Pipelines running from wellheads to downstream facilities frequently have a need for a source of power to operate related equipment. The need for power frequently occurs at locations well off the power grid.
Environmental agencies prefer, or dictate, that a source of such power produce no undesirable emissions, as might a gasoline powered generator. Regulatory authorities prefer sources of power along pipelines to be green. Frequently this dictates that the source of power be a battery and that the battery be charged by a green source of power such as solar or wind. However, it is well known that solar and wind power are not 100% reliable. Other difficulties with solar or wind power include seasonally diminished performance, high cost, wear and tear on batteries and lack of continuity. The instant invention proposes to use the motive force of the fluid flowing through the line as a source of, or a supplemental source of, power for a turbine and generator, the turbine and generator generally structured and scaled to be of a size sufficient to maintain charge on a 12-volt battery. Further, in the circumstances of the production of sour gas, there is significant concern associated with creating any new opening in a pre-existing line, creating thereby a potential for the deadly escape of sour gas. Hence, an inline generator is preferred in such circumstances which can utilize a pre-existing safeguarded valve opening in a line, the valve existing for such purposes as the insertion of other instruments, such generator to be preferred from an overall safety and maintenance standpoint.
In general, challenges faced in producing natural gas include pipe corrosion, sour gas as mentioned above and restrictions on the production of water as well as other EPA and OSHA regulations. Typically, thus, at a natural gas well site there is found a wellhead, a separator, water tanks, flow lines, a chemical injection pump system, measuring instrumentation, a lighting system and pipelines. Chemicals injected may include corrosion inhibitors, scale inhibitors, H2S scavengers, foamers and bio-sides. In particular, a line containing sour gas from a wellhead to a downstream facility is frequently associated with a chemical injection pump.
One very significant problem with pipe lines running from a wellhead to downstream facilities is that the pipeline may include sour gas, or hydrogen sulfide (H2S), as mentioned above. H2S at over 200 ppm can be deadly. Pipeline regulations require gas to be under 4 ppm H2S before entry into the pipeline. Further, H2S dissolved in water creates an acidic solution that increases the corrosion rate and leads to early pipe failure. For such reasons chemicals are typically injected by a chemical injection pump into the fluid flow in a pipeline, proximate the wellhead. Among other reactions, the chemicals react to H2S causing bonds to be broken and allowing sulfur to precipitate out. A constant flow of chemical will be typically desired for optimal results, and it is important that the chemical pumps perform adequately and reliably.